This invention relates generally to a textile machine and, more particularly, to a warper for drawing multiple textile strands from a supply such as a creel and for winding the strands on a rotatable drum or beam.
In such a warper, rollers are located between the creel and the beam to guide the strands from the creel to the beam. One of the rollers is a delivery roller and is rotated by a motor which causes the roller to draw strands from the creel and to supply the strands to the beam. Two nip rollers are tangent to the delivery roller and coact with the latter to guide the strands and to isolate the tension in the strands at the beam from the tension of the strands at the creel. If a strand breaks, brakes associated with the beam and the delivery roller automatically bring the two to a stop in order to enable the machine operator to repair the break.
It is important to maintain a substantially constant tension in the strands being wound on the beam. An increase in the tension at the beam will result in an increase in the density of the strands wound on the beam because the high tension causes the strands to pack tightly on the beam. Conversely, a decrease in the tension will cause the density of the strands on the beam to decrease.
Various arrangements have been provided to control the tension of the strands at the beam. One of the more common arrangements involves controlling the torque applied by the delivery roll motor to the delivery roll so as to reduce the torque if the tension at the beam increases and to increase the torque if the tension at the beam decreases. Conventionally, the delivery roll motor is controlled by sensing the current drawn by the motor and by changing the power input to the motor as a function of changes in such current. This type of control system, however, lacks accuracy since changes in current result only in a rough approximation of changes in strand tension. Changes in motor current are not only dependent upon changes in tension but also upon extraneous factors such as belt slippage and variations in other intervening drive components between the motor and the delivery roller.